Flies of North America - Order Diptera
Flies Index | Tachinidae | Syrphidae | Bee Flies | Blow Flies | Flesh Flies | Robber Flies

True flies, two-winged flies are prevalent in virtually all habitats, with over 16,000 species in North America. Live adults and maggots photographed in the wild at North American locations.
Syrphid Fly - Spilomyia longicornis
Spilomyia longicornis
Flies are prevalent in virtually all habitats, with over 16,000 species in North America. Flies can be distinguished from all other insects in that they only have one pair of normal wings. Most flies have compound eyes and mouthparts adapted for piercing, lapping or sucking fluids.
Flies are some of the most deadly carriers of disease; millions still die from mosquito-carried malaria every year; countless thousands fall victim to yellow fever, typhoid and dysentery, all caused by fly-born bacteria. On the other hand, flies are important pollinators, scavengers, and parasites of other harmful insects.
Family Asilidae - Robber Flies comprise over 7,000 species world- wide; nearly 1,000 in North America. All robber flies have stout, spiny legs, a dense moustache of bristles on the face (mystax), and 3 simple eyes (ocelli) in a characteristic depression between their two large compound eyes. The mystax helps protect the head and face when the fly encounters struggling prey.

The antennae are short, 3-segmented, sometimes with a bristle-like structure called an arista. The short, strong proboscis is used to stab and inject victims with saliva containing neurotoxic and proteolytic enzymes which paralyze the unfortunate and digest the insides; the fly then sucks the liquefied meal much like we vacuum up an ice cream soda through a straw. Many species have long, tapering abdomens, sometimes with a sword-like ovipositor. Others are fat-bodied bumble bee mimics.

Robber flies are among the largest of the predatory flies; they can not only look like bumble bees, they can sound like them too!

Family Asilidae
Laphria thoracica
Bombyliidae - Bee Flies
Bombylius major
Family Bombyliidae - Bee Flies make up one of the largest families, with over 5,000 species described worldwide. Their high diversity may be due to the parasitoid habit of the majority of their larvae. Adults feed on nectar and pollen, and are believed to be important pollinators of many plants although few species have been studied in detail. Bee flies occur on all continents except Antarctica.

I most often see bee flies hovering around flowers, or if resting, usually on bare soil. They are extremely wary and difficult to approach. No doubt their large compound eyes give them good vision, plus they have that air-motion sensing mechanism that helps the ordinary house fly avoid the swatter. Adult bee flies drink nectar, but the larvae are parasites of beetle larvae as well as the brood of solitary burrow-nesting wasps and bees.

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Family Calliphoridae - Blow, Bottle, and Screwworm Flies
Most blow flies lay their eggs almost exclusively in dead or rotting flesh. A few species' larvae are parasitic on bird nestlings, some have larvae that live as internal parasites of mammals [1]. They are usually the first insects to arrive at a fresh carcass, sometimes within minutes of death; they are attracted by the organic odors of  decomposition. Eggs are laid around natural body orifices or open wounds, and the larvae molt and pupate at predictable rates for any given ambient temperature and humidity; it is for these reasons the blowflies are so important in forensic pathology. Maggots (larvae) and pupariums (the hollow cases left behind after the adult fly emerges) collected from a body can be used to determine, sometimes very accurately, the time of death.

Some species in the family are serious pests of livestock, especially in the tropics. They cause myiasis, a condition in which their larvae inhabit the skin or connective tissue of large mammal hosts. Larvae of some bot flies (Oestridae), and flesh flies (Sarcophagidae) also use this parasitic stage.

Family Calliphoridae
Family Conopidae - Thick-Headed Flies
Family Conopidae - Thick-Headed Flies are often found at flowers feeding on nectar with their long proboscis. This wonderful contraption resembles the spout on the old railroad trackside water towers used during the steam era, or the boom used in mid-air refueling operations.

Conopidae are distributed in all the zoogeographic regions except for the poles and many of the Pacific islands. About 800 species are described worldwide, approximately 67 of which are found in North America. The majority of conopids are black and yellow, or black and white, and often strikingly resemble wasps, bees, or flies of the family Syrphidae, themselves notable bee mimics. The larvae of all conopids are internal parasites, most of aculeate (stinging) Hymenoptera. Adults are said to alight and deposit eggs on their flying hosts.

Crane Flies - Infraorder Tipulomorpha
From Latin tipula "water spider." If you've ever seen one, you'll know why the people of Scandinavia and Great Britain call them daddy long legs. The common name refers to the long-legged wading birds. They are most often found in moist woodlands and around water, where their larvae often spend their developmental stage.

Adults have a relatively short lifespan of 10-15 days, although the entire brood may last a month or more.  The larvae are found in a wide variety of habitats, varying from strictly aquatic to terrestrial [1].

There are ~1500 species of crane fly in North America, and over 15,000 worldwide.  Most species pictured here are members of Family Tipulidae, often referred to as "large" crane flies, with 4,269 recognized species [2].

Infraorder Tipulomorpha
Tipula bicornis
Aedes taeniorhynchus
Family Culicidae - Mosquitoes
Mosquitoes are estimated to transmit disease to more than 70 million people annually in Africa, South America, Central America, Mexico and much of Asia with millions of resulting deaths. In Europe, Russia, Greenland, Canada, the United States, Australia, New Zealand, Japan and other temperate and developed countries, mosquito bites are now mostly an irritating nuisance, but malaria and other warm-weather diseases are slowly moving northward as our atmosphere and hydrosphere warm due to increasing greenhouse gas concentrations.

Mosquitoes were shown to be the method by which yellow fever and malaria were transmitted from person to person by Walter Reed, William C. Gorgas and associates in the U.S. Army Medical Corps first in Cuba and then around the Panama Canal in the early 1900s. Since then other diseases have been shown to be transmitted the same way.

Golden Dung Fly
Dung Flies - Family Scathophagidae is a small group commonly called dung flies, although only a few species' larvae actually spend their development in dung exclusively. Many others' larva are plant feeders (leaf miners, stem-borers), aquatic predators and predators on other insect larvae resident in rotting vegetable matter, seaweed or dung. The adults are predators of other small insects as well as eating pollen and taking nectar from flowers. They are prolific predators of blow flies.

Worldwide, there are about 360 described species in 66 genera. The great majority are found in the Palearctic and Nearctic regions and the family is almost wholly confined to the northern hemisphere; only 5 species are known from the southern hemisphere.
Family Sarcophagidae - Flesh Flies
Flesh flies differ from the tachinid flies in that they lack the postscutellum, the large swelling underneath the scutellum on the thorax. Flesh flies have a prominent row of bristles (setae) on each side of the thorax just above the base of the hind leg in addition to another row of bristles just under the base of the wing. These two sets of bristles differentiate the flesh flies from the Muscid flies; they rarely have both sets.

Flesh Flies most resemble blow flies, but are never metallic colored. They generally have highly contrasting black and grey stripes on the thorax, as well as a checkerboard-like pattern on the abdomen. Flesh flies also always have 4 rather than 2 or 3 bristles atop the thorax.

Family Sarcophagidae - Flesh Flies
Flesh Fly - Bellieria sp.
Family Syrphidae
Spilomyia longicornis
Family Syrphidae are often called syrphids, hover flies, flowers flies or sweat bees. Despite their sometimes very convincing mimickry of the bees and wasps, these gentle creatures do not bite or sting. Adults feed on pollen and nectar, larvae eat plant materials or are predators on other insects, most notably aphids.

As such, Syrphid flies are routinely used as a biological control agents in many agricultural crops. In the lettuce fields of California's vegetable-producing regions, the fly's larvae are effective in controlling lettuce aphid. It is primarily the Syrphidae that enable organic romaine growers on California's central coast to produce harvestable crops.

Syrphidae larvae are, in turn, parasitized by wasps in the Hymenoptera families Ichneumonidae, Braconidae and Pteromalidae [3].

Family Tachinidae is the second-largest family of Diptera, with over 10,000 species worldwide. Adult tachinid flies are known for their bristly facies. Archytas exhibits prototypical tachinid features, including a large, metallic-colored abdomen covered with bristles. Many other tachinids, however, are sparsely bristled and exhibit very pale coloration. All Tachinids share the parasitoid habit, and almost all of them are endoparasites of other insects; in spite of their varied appearance all species of Tachinidae are alike in this characteristic [4].

Insects most commonly parasitized by the tachinids are the larvae of the Lepidoptera (butterflies and moths) and the adults and larval form of the beetles. Other tachinids attack true bugs of the Hemiptera (Heteroptera), larvae of Hymenoptera (bees, wasps, ants, sawflies), and adults of Orthoptera (grasshoppers, katydids, crickets and their kin).

Adejeania vexatrix
Family Tabanidae
Deer Fly Chrysops calvus
Family Tabanidae - Horse and Deer Flies
are unusual in the fly kingdom: their flight can be nearly silent. They are famous for landing on exposed skin and delivering a painful bite. I can tell you from bitter experience, these flies can take a licking as well. I have delivered many a brutal slap to these creatures, only to watch in wonder as they get up and fly away. Only females bite; the males feed mainly on nectar and pollen at flowers.
Family Tephritidae
Family Tephritidae - Large Fruit Flies
There are nearly 5,000 described species of tephritid fruit fly in almost 500 genera. To distinguish them from the Drosophilidae, the Tephritidae are sometimes called "peacock flies."

Tephritid fruit flies are of major importance in agriculture. The genus Bactrocera is of worldwide notoriety for its destructive impact on agriculture. The olive fruit fly (B. oleae) feeds on only one plant: the wild or commercially cultivated olive. It has the capacity to ruin 100% of an olive crop by damaging the fruit.

Most fruit flies lay their eggs in plant tissues, where the larvae find their first food upon emerging. The adults usually have a very short lifespan. Some live for less than a week. Some tephritids have mating rituals or territorial displays.
  1. Chen Young, Carnegie Museum of Natural History, "Crane Flies of Pennsylvania"
  2. P. Oosterbroek, "Catalogue of the Craneflies of the World"
  3. University of California, DANR, "Biological Control Agents for Aphids in Vegetable Crops"
  4. Bugguide.net, "Family Tachinidae"
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Flies of North America - Order Diptera. Flies are prevalent in virtually all habitats, with over 16,000 species in North America. Flies can be distinguished from all other insects in that they only have one pair of normal wings. Most flies have compound eyes and mouthparts adapted for piercing, lapping or sucking fluids. Insects & Spiders | Flies Index | Syrphidae | Bee Flies | Robber Flies
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